I've been on FB for 8 or 9 years - just discovered the neighbourhood groups in the past year - been amazed what I've learned about what's going on here. Our immediate police detachment is looking at adding a second social media person as so much information comes in that way - and that is how they keep us updated on stuff like gang projects, more feet on the street, missing people.
Recently, someone in the neighbourhood posted a short video of someone stealing his bike and kid-wagon. Other people id'd another video floating around of the same guy using a stolen credit card at McDonald's - his ex-girlfriend's friends gave info about where he tended to hang out and, boom, he was arrested. It showed up on three neighbourhood groups and in our police feed. It was kind of amazing to watch.